A processing device implementing unbounded transactional memory with forward progress guarantees using a hardware global lock is disclosed. A processing device of the disclosure includes a hardware transactional memory (HTM) hardware contention manager to cause a bounded transaction to be translated to an unbounded transaction, the unbounded transaction to acquire a global hardware lock for the unbounded transaction, the global hardware lock read by bounded transactions that abort when the global hardware lock is taken. The processing device further includes an execution unit communicably coupled to the HTM hardware contention manager to execute instructions of the unbounded transaction without speculation, the unbounded transaction to release the global hardware lock upon completion of execution of the instructions.